Need Differential Help
Thread Starter
Instructor
Joined: Jun 2001
Posts: 139
Likes: 0
From: Coral Springs FL
Need Differential Help
How much HP can be put to a 1980 vette rear and drag race? I have a 1980 vette with 700R4, 2800 stall converter, 3.73 rear gears, and had a ZZ4 355 HP and no problem. Launch at 2200 RPM and ran 1.68 60 foot times. Just put in a ZZ383 with 425 HP and ran 1.59 60 foot times. !0 passes and rear sounds like it's going. Anyone have info on what I can run, any after market parts?, maybe going to a 4.11 gear set would help?, anyone have telephone number of Tom's differential in CA, allways heard he was the expert.
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
How much HP can be put to a 1980 vette rear and drag race? I have a 1980 vette with 700R4, 2800 stall converter, 3.73 rear gears, and had a ZZ4 355 HP and no problem. Launch at 2200 RPM and ran 1.68 60 foot times. Just put in a ZZ383 with 425 HP and ran 1.59 60 foot times. !0 passes and rear sounds like it's going. Anyone have info on what I can run, any after market parts?, maybe going to a 4.11 gear set would help?, anyone have telephone number of Tom's differential in CA, allways heard he was the expert.
Thread Starter
Instructor
Joined: Jun 2001
Posts: 139
Likes: 0
From: Coral Springs FL
Thanks 63mako, how do I get in touch with gtr1999 or tracdogg2? Also is there an iron pumpkin made for a 1980 batwing? The problem I think is the aluminim case can,t handle the power, the caps are the weak link.
Drifting
Joined: Jul 2009
Posts: 1,532
Likes: 14
From: Dallas-Fort Worth TX
There is a friend of GTR1999 in Texas that rebuild the aluminum rear ends and uses steel caps. Other wise if you go to a iron differential, you will have to use different drive/half shafts, strut rods, etc. I hear its big pain, but it can be done. It will add more weight back to the car but it will be stronger. Also check out BeeJay, I think that is his username. He has a 70's model with a aluminum bat wing and Iron differential. Looks like a lot of custom wellding was required, but it came out nice from the pics I saw and he seems to be happy with it.
You will see many opinions about the aluminum rear ends and their weakness, but unless your going to drag race with slicks, manual transmission and all, the aluminum rear ends will hold up and take a beating with high HP engines. But it does sound like you visit the track often, so do your research.
Good luck,
You will see many opinions about the aluminum rear ends and their weakness, but unless your going to drag race with slicks, manual transmission and all, the aluminum rear ends will hold up and take a beating with high HP engines. But it does sound like you visit the track often, so do your research.
Good luck,
Le Mans Master
Joined: Apr 2007
Posts: 7,353
Likes: 72
From: Graceland in a Not Correctly Restored Stingray
Taxing the IRS
In case you haven't already read this...
http://hotrod.automotive.com/79266/0...tup/index.html
By all accounts, the stock C3 iron 10-bolt IRS diff is stronger than the later model batwing design, but will eventually fail given enough torque and bite, even on street tires (BTDT). A well prepared 10-bolt will take a good bit more punishment. FYI, the batwing can be adapted to mate to a 10-bolt. Stronger still is the 12-bolt conversion (
), but the factory batwing apparently hasn't enough material to accept it.
In any event, a diff must obviously be built to very high standards if it is going to survive severe duty for long, and IMCO GTR1999 is likely as good as there is at it. Not familiar with Tracdogg2, but his rep aruond here is also very good. Tom's no longer assembles the 12-bolts, BTW. Hope that's worth $.02
TSW
edit - The C3/D44 batwing can be adapted to accept a 12-bolt IRS diff with a spacer/mid-plate to make up for lack of material.
http://hotrod.automotive.com/79266/0...tup/index.html
By all accounts, the stock C3 iron 10-bolt IRS diff is stronger than the later model batwing design, but will eventually fail given enough torque and bite, even on street tires (BTDT). A well prepared 10-bolt will take a good bit more punishment. FYI, the batwing can be adapted to mate to a 10-bolt. Stronger still is the 12-bolt conversion (
), but the factory batwing apparently hasn't enough material to accept it. In any event, a diff must obviously be built to very high standards if it is going to survive severe duty for long, and IMCO GTR1999 is likely as good as there is at it. Not familiar with Tracdogg2, but his rep aruond here is also very good. Tom's no longer assembles the 12-bolts, BTW. Hope that's worth $.02
TSW
edit - The C3/D44 batwing can be adapted to accept a 12-bolt IRS diff with a spacer/mid-plate to make up for lack of material.
Last edited by TheSkunkWorks; Oct 1, 2011 at 09:52 PM.
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
Tracdogg2 is from Texas. He can build the stock rear as strong as it can be built. Both are forum members so do a search and PM or e-mail them. The iron pumpkin can be installed in the batwing. I havent done it but it is not that difficult. You need the pumpkin, halfshafts, strut rods and bracket and some basic fabricating skills.
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Le Mans Master
Joined: Feb 1999
Posts: 8,351
Likes: 75
From: Tampa Bay FL
I had a new (service replacement) unit installed in my '80 L48 back around 2001. At the time, I had the unit blueprinted and 3.54 spicer gears installed. The shop, Alan's GearWorks in Clearwater, FL, said the rebuilt/blueprinted unit could easily handle 400hp. I wouldn't subject a worn unit to that level of hp. A rebuilt/blueprinted unit? Absolutely!!!
NOTE: Alan's actually set the unit up with much stricter tolerances than GM. At the time, Alan was still working there. He demonstrated the removed ring/pinion and the set he had installed and how the paint/chalk marks where the teeth meshed were 'better' on the blueprinted unit. His claim was that with less 'slop' in how the gears mesh, you will get better performance and less likelihood of breakage. Granted this was 9 years ago and my recall may be clouded but that is what I took away from the conversation.
NOTE: Alan's actually set the unit up with much stricter tolerances than GM. At the time, Alan was still working there. He demonstrated the removed ring/pinion and the set he had installed and how the paint/chalk marks where the teeth meshed were 'better' on the blueprinted unit. His claim was that with less 'slop' in how the gears mesh, you will get better performance and less likelihood of breakage. Granted this was 9 years ago and my recall may be clouded but that is what I took away from the conversation.
Last edited by TedH; Mar 31, 2010 at 05:13 PM.
Le Mans Master
Joined: Feb 1999
Posts: 8,351
Likes: 75
From: Tampa Bay FL
How much HP can be put to a 1980 vette rear and drag race? I have a 1980 vette with 700R4, 2800 stall converter, 3.73 rear gears, and had a ZZ4 355 HP and no problem. Launch at 2200 RPM and ran 1.68 60 foot times. Just put in a ZZ383 with 425 HP and ran 1.59 60 foot times. !0 passes and rear sounds like it's going. Anyone have info on what I can run, any after market parts?, maybe going to a 4.11 gear set would help?, anyone have telephone number of Tom's differential in CA, allways heard he was the expert.
http://www.agearworks.com/
Thread Starter
Instructor
Joined: Jun 2001
Posts: 139
Likes: 0
From: Coral Springs FL
Wish I had checked this out on the forum last year, had a broken end cap and guy sold me a used case plus rebuild. Was told you couldn't replace an end cap because it had to be bored like a main journal. I like the steel end cap as shown by tracdogg2. This looks like my solution and with a little more caution on my burnouts and launch I should be okay. Thanks everyone for the input.
Race Director
Joined: Jan 2003
Posts: 15,175
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From: State of Confusion
Wish I had checked this out on the forum last year, had a broken end cap and guy sold me a used case plus rebuild. Was told you couldn't replace an end cap because it had to be bored like a main journal. I like the steel end cap as shown by tracdogg2. This looks like my solution and with a little more caution on my burnouts and launch I should be okay. Thanks everyone for the input.
how-quick & fast do you think you'll go with the ZZ383
Thread Starter
Instructor
Joined: Jun 2001
Posts: 139
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From: Coral Springs FL
With my ZZ4 best times were 1.68 60 foot, 8.13 1/8 mile @ 82.14 MPH, 12.84 1/4 mile et @ 103. 750 CFM quick fuel carb, 2800 stall converter, 700R4 trans, 3.73 rear, 275x60x15 M/T drag radials or 26x10.5x15 M/T slicks. The really low 1st gear in the R700 (3.06) gives it the quick short time, and then dies when it hits 2nd. After swapping in ZZ283 and only 10 runs, still needs some tweeking, 1.59 60 ft, 7.696 1/8 mile @87.40 MPH, 12.17 et @ 109.80 MPH. (1 pass @ 112.08 MPH?)
Last weigh in was at 3350 lbs. Have added some weight, NOS 30 lbs, trailer hitch, channel iron under side frame to protect low side ground kit.
With a 100 shot of NOS at 2nd gear for 6 seconds at a pink meet, the ZZ4 ran 12.03 et. Will have to post some pictures.
Last weigh in was at 3350 lbs. Have added some weight, NOS 30 lbs, trailer hitch, channel iron under side frame to protect low side ground kit.
With a 100 shot of NOS at 2nd gear for 6 seconds at a pink meet, the ZZ4 ran 12.03 et. Will have to post some pictures.
Safety Car
Joined: Nov 2008
Posts: 3,716
Likes: 551
From: Seattle Washington
Installing a Steel Cap (s) dose require Machineing like a Align Bore.Might look at Tracy Corvette for info. What u-joints do You have? If your 80' was an Auto like most of them were they will give up and break a lot of body parts long before the Diff goe's. You need 80-81 4 speed or any 82' that uses the Spicer 1350 u-joint. To do this you will need the Diff Yokes, 1/2 Shafts and Axel Flanges and of Coarse the U-Joints. The above mentioned Iron Pumkin is the 63-79 Vette Diff that is bolted to Your Aluminum Batwing. Yes it will bolt on. If you go that route then You will need the above mentioned 1/2 shaft parts but for the earlier Rear instead. Oh and a Strut Rods and a brackets from an earlier car as well.
Thread Starter
Instructor
Joined: Jun 2001
Posts: 139
Likes: 0
From: Coral Springs FL
Yes I did the axle change and half shafts with outer flanges about 3 years ago and have had no problems. Before that I broke at the track at least once a month. Had to buy u-joints by the dozen.
